sparc64: Fix incorrect ASI_ST_BLKINIT_MRU_S value

ASI_ST_BLKINIT_MRU_S is incorrectly defined as 0xf2 when it
should be 0xf3 according to section 10.3.1 of the Sparc
Architecture manual.

Signed-off-by: Rob Gardner <rob.gardner@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>